The present invention relates to positioning apparatus, in general, and to apparatus for controlling the movement of a positioning or force generating device commonly referred to as an industrial robot, in particular.
Automated product assembly machines, for example, have been employed in manufacturing industries for a great number of years. More recently, though, technologically more sophisticated machines have been employed for such purposes. These more recent machines are commonly referred to as industrial robots. Industrial robots are capable of performing various mechanical operations with a high degree of speed and accuracy in response to a set of programmed instructions.
Common uses for industrial robots include the movement of a workpiece from one position to another and the performance of repetitive operations with a high degree of precision. The use of industrial robots in place of human personnel has proven very beneficial in that they have resulted in both cost reductions and processing accuracy and have relieved many personnel from performing routine and/or potentially hazardous jobs. Industrial robots are also employed in numerous other fields of technology to perform a variety of different operations.
A significant problem associated with industrial robots, especially those employed for product assembly purposes, is their inability to recognize when they collide or make contact with objects located in their paths of travel when moving to perform programmed tasks. Inasmuch as most industrial robots are capable of generating extremely large physical forces, such forces can seriously damage or even destroy such contacted objects, objects that have heretofore been undetectable when struck or contacted by any portion of a moving robot. A typical object damaging situation often occurs when an industrial robot is programmed to place a series of identical objects or piece-parts into fairly close tolerance openings or recesses in, for example, a series of identical housings, during product assembly, over an extended period of time. During this extended period of product assembly time, a gradual misalignment will often result between, for example, the center of the housing opening and the center of the piece-part that is being inserted into the housing opening, misalignment that has heretofore been undetectable. The consequences of the robot being unable to detect such misalignment often is damage to the piece-part, to the housing or to the robot itself because of the large physical forces likely to be involved as the robot blindly attempts to place a piece-part in a misaligned housing opening where it is incapable of detecting such misalignment.
A primary object of the present invention is to provide apparatus for detecting relative movement between members that are resiliently attached to one another.
Another object of the present invention is to provide apparatus for determining when a portion of an industrial robot arm comes in contact with a robot arm-motion impeding object.
Another object of the present invention is to provide apparatus for terminating movement of an industrial robot whenever a portion of said robot strikes or comes in contact with a movement-impeding object.
A further object of the present invention is to provide apparatus that will enable an industrial robot to apply a predetermined physical force to a particular object or workpiece such as when components are required to be forced together during product assembly.
A still further object of the present invention is to provide apparatus for accurately determining the initial or null position of a robot hand for minimum time consuming, initial robot hand position-describing, robot arm programming purposes.
Other objects, features and advantages of the present invention will be readily apparent from the following description of the preferred embodiment thereof taken in conjunction with the accompanying drawings.